The present invention relates to an information transmitting device and a transmitting method, and is suitably applied to a digital broadcasting system which broadcasts upon digitalizing information such as video and audio for example.
Heretofore, various compression encoding systems have been proposed to decrease the volume of information of video and audio. One representative system is a compression encoding system called MPEG2 (Moving Picture Experts Group Phase 2) which is standardized by the organization such as ISO (International Organization for Standardization). The MPEG2 system has been standardized in order to transmit video and audio.
In recent years, a digital broadcasting system has been devised, which compression-encodes video and audio utilizing the MPEG2 system and broadcasts the compression-encoded video and audio utilizing the ground wave and satellite wave. In the digital broadcasting system, encoded video data and audio data are packetted for every fixed block and the resultant packet lines are transmitted (hereinafter, the packet line is referred to as a transport stream and the packet for generating the transport stream is referred to as a TS (transport stream) packet). In this case, the transport stream packet (TS packet) is comprised of a data section and a header section as shown in FIG. 1, and wherein the data section stores video data and audio data to be transmitted and the header section stores a synchronous byte and a packet identifier (hereinafter, referred to as PID) or various other packet control data. In this connection, the synchronous byte is data showing the beginning of packet and the PID is data showing the content of information stored in the packet.
Further, in the digital broadcasting system, by packetting the data to be transmitted, video and audio data of plural programs are multiplexed so that plural programs can be broadcast through one circuit. However, in the case of multiplexing data of plural programs, the receiver side must extract and decode the TS packet in which the video data and audio data of the program desired by an audience have been stored, from the transmitted TS packets. Therefore, the extracting work makes the process of the receiver side complicated.
Thus, in the digital broadcasting system, additional information on the program called program specific information (PSI) is packetted and transmitted, and the receiver side refers to the PSI to extract and decode the TS packet having the desired program. In this connection, in case of packetting the PSI, the PSI is stored in the data section having the packet structure shown in FIG. 1.
The PSI is roughly classified into a program map table (PMT), a program association table (PAT), a conditional access table (CAT), and a network information table (NIT). The PMT is a corresponding table (hereinafter, referred to as a table) showing the PID values of the TS packets in which video data and audio data to form the program are stored. For example, in the program number xe2x80x9cXxe2x80x9d, the table shows that the video is PID=xe2x80x9cXVxe2x80x9d and the audio is PID=xe2x80x9cXAxe2x80x9d. Further, the PAT is a table showing the PID value of the TS packet in which the PMT is stored. For example, the table shows that the PMT with the program number xe2x80x9c0xe2x80x9d is PID=xe2x80x9cAAxe2x80x9d, the PMT with the program number xe2x80x9c1xe2x80x9d is PID=xe2x80x9cBBxe2x80x9d, and the PMT with the program number xe2x80x9cXxe2x80x9d is PID=xe2x80x9cXXxe2x80x9d. Further, the CAT is a table showing the PID value of the TS packet in which lock code decipher information for deciphering the scrambled video and audio data is stored. Furthermore, the NIT is a table showing the PID value of the TS packet in which physical information on transmission route is stored, and the PID value of the TS packet in which the NIT is stored is designated by the PAT.
When the PSI is transmitted, the receiver side first obtains the PAT by extracting the TS packet in which the PAT has been stored, examines the TS packet in which the PMT for the program desired by the audience has been stored by referring to the PAT, and obtains the PMT by extracting the corresponding TS packet. Then, the receiver side refers to the PMT to examine the TS packet in which video and audio data of the program desired by the audience, and extracts the corresponding TS packet to obtain and decode the video and audio data. Thereby, the program desired by the audience can be easily reproduced.
Note that, in the digital broadcasting system, additional information on a program called service information (SI) is transmitted other than aforementioned information, and is utilized with various forms at the receiver side. In this connection, the SI is classified into a bouquest association table (BAT), a service description table (SDT), an event information table (EIT), a time and date table (TDT), a running status table (RST), a stuffing table (ST), and so on. And the detailed SI is disclosed in the literature xe2x80x9cDigital Broadcasting Systems for television, sound and data services; Specification for Service Information (SI) in Digital Video Broadcasting (DVB) systems (ETS 300468)xe2x80x9d published by the Europe electric transmission standardization association (ETSI).
In this connection, the PID values of TS packets in which the aforementioned PSI and SI or video data and audio data are stored are determined in advance as shown in FIG. 2. More specifically, the PAT is stored in the TS packet having the xe2x80x9c0X0000xe2x80x9d PID, and the CAT is stored in the TS packet having the xe2x80x9c0X0001xe2x80x9d PID. Further, the TS packet having the xe2x80x9c0X0010xe2x80x9d PID stores the NIT and ST, the TS packet having the xe2x80x9c0X0011xe2x80x9d PID stores the SDT, BAT, and ST, the TS packet having the xe2x80x9c0X0012xe2x80x9d PID stores the EIT and ST, the TS packet having the xe2x80x9c0X0013xe2x80x9d PID stores the RST and ST, and the TS packet having the xe2x80x9c0X0014xe2x80x9d PID stores the TDT. Furthermore, the TS packets having from the xe2x80x9c0X0020xe2x80x9d PID to the xe2x80x9c0X1FFExe2x80x9d PID store the PMT and NIT or video data and audio data.
By the way, in the case of realizing the digital broadcasting system described above, the construction shown in FIG. 3 will be generally considered. More specifically, as shown in FIG. 3, a digital broadcasting system 1 is comprised of a transmitting device 2 which is equivalent to a broadcasting station, for encoding and transmitting video and audio data, and a receiving device 3 which is installed in each home, for receiving and decoding the data transmitted from the transmitting device 2.
In such the digital broadcasting system 1, when the transmitting device 2 receives a transport stream multiplexed at another transmitting device and newly multiplexes another program onto the multiplexed transport stream to transmit it, the receiving device 3 must surely receive it on the basis of the additional information of packet.
Further, in the digital broadcasting system shown in FIGS. 1 to 3, when such the PSI is transmitted, the receiver side first extracts the TS packet having the xe2x80x9c0X0000xe2x80x9d PID in which the PAT has been stored in order to obtain the PAT, and then extracts TS packet in which PMT for the program desired by the audience has been stored, by referring to the PAT in order to obtain the PMT. Next, the receiver side examines the TS packet in which the video and audio data of the program desired by the audience has been stored, on the basis of the PMT, and extracts the TS packet to obtain and decode the video and audio data. Thus, the receiver side can easily reproduce the program desired by the audience.
The present invention intends to propose an information transmitting device and transmitting method including other transmitting devices, which can surely decode data with a simple construction as possible in the case of multiplexing and transmitting a plurality of packet lines outputted from a plurality of encoding means.
The present invention comprises a plurality of encoding means for encoding inputted input data, and packetting and outputting the encoded data for every fixed block, an additional information generating means for generating first additional information on the packetted input data and packetting and outputting the first additional information, a signal separating means for separating a packet line multiplexed by another transmitting device into a packet line of element data and a packet line of second additional information on the element data, an additional information regenerating means for combining the first additional information and the second additional information to generate one piece of third additional information, and packetting and outputting the third additional information, and a multiplexing means for multiplexing the packet line of third additional information, a plurality of packet lines outputted from the plurality of encoding means, and the packet line of element data to convert them into one packet line, and outputting it.
In this way, the packet line multiplexed by the other transmitting device is separated into a packet line of element data and a packet line of the second additional information on the element data, and then, the third additional information is generated by combining the first additional information and the second additional information. Thereby, the overlap of additional information can be avoided with a simple construction.
Further, the present invention comprises a plurality of encoding means for encoding inputted input data, and packetting and outputting the encoded data for every fixed block, a signal separating means for separating a packet line multiplexed by another transmitting device into a packet line of element data and a packet line of first additional information on the element data, an additional information generating means for receiving the packet line of the first additional information, generating third additional information by adding the first additional information to the second additional information on the packetted input data, and packtting and outputting the third additional information, and a multiplexing means for converting the packet line of the third additional information and a plurality of packet lines outputted from the encoding means and the packet line of element data into one packet line by multiplexing, and sending the packet line.
In this way, the packet line multiplexed by another transmitting device is separated into the packet line of element data and the packet line of the first additional information on the element data, and the third additional information is generated by adding the first additional information to the second additional information on the packetted input data. Thereby, the overlap of additional information can be avoided without regenerating additional information, thus the overlap of additional information can be avoided with further simple construction.
Further, the present invention provides a packet identifier correcting means for correcting packet identifiers so that the packet identifier added to each packet of element data is different from the packet identifier added to each packet outputted from the encoding means. In this way, the packet identifier correcting means is provided to correct the packet identifiers, thereby the overlap of packet identifiers can be easily avoided.
Further, the present invention provides a plurality of encoding means for encoding input data, and packetting the encoded data for every fixed block and adding a packet identifier to the generated packet to output it, a control means for controlling packet identifiers which are added by the encoding means and for instructing the plurality of encoding means to add packet identifiers different from each other, and a multiplexing means for multiplexing a plurality of packet lines outputted from the plurality of encoding means to form one packet line and outputting the packet line.
Accordingly, the control means controls the packet identifiers to instruct the plurality of encoding means so as to add packet identifiers different from each other, and the plurality of encoding means add the packet identifiers in accordance with the instruction. Thereby, the overlap of packet identifiers can be easily avoided without regenerating packet identifiers added by the respective encoding means.
Furthermore, the present invention provides a plurality of encoding means for encoding input data, and packetting the encoded data for every fixed block and adding packet identifiers to the generated packets to output them; an additional information generating means for generating additional information showing the relationship between the input data and the packet identifier, on the basis of the packet identifier which is added by the encoding means, and packetting and outputting the additional information; and a multiplexing means for converting a plurality of packet lines outputted from the plurality of encoding means and a packet line of the additional information into one packet line by multiplexing and sending the packet line.
Accordingly, since an additional information generating means is provided separately from the encoding means to generate additional information on the basis of the packet identifier which is added by the encoding information without generating additional information respectively by a plurality of encoding means, the additional information matching to the multiplexed packet line can be generated without regenerating the additional information.